喹啉型双子季铵盐缓蚀剂的实验及理论分析

以喹啉为母体、 1,4-对二氯苄和顺-1,4-二氯-2-丁烯为联结基, 制备了2种具有疏水结构的水溶性双喹啉季铵盐(BQA-1和BQA-2). 通过失重实验、 电化学测试、 扫描电子显微镜(SEM)及量子化学计算等手段研究了BQA-1和BQA-2对1 mol/L盐酸中Q235钢的缓蚀性能, 并讨论了其在Q235钢表面的吸附机理. 失重结果显示, BQA-1和BQA-2对盐酸中的钢片均具有良好的缓蚀效果, 30 ℃下, 当浓度为0.5 g/L时, BQA-1和BQA-2的缓蚀率均超过94.59%; 升温导致BQA-2的脱附速率比BQA-1更快. 电化学测试结果显示, BQA-1和BQA-2是以抑制阴极为主的混合型缓蚀剂. 分析热力学参数可知, BQA-1和BQA-2在钢表面的吸附为自发、 放热过程, 符合Langmuir等温式, 且以化学吸附为主. 量子化学计算结果表明, BQA-1和BQA-2的吸附活性集中在喹啉环及杂原子上, 且BQA-1和BQA-2分子得电子与Fe作用的能力要强于供电子与Fe作用的能力.

Experimental and Theoretical Analysis of Quinoline Diquaternary Ammonium Salt as Corrosion Inhibitor †

Two water-soluble bisquinoline quaternary ammonium salts with hydrophobic structures(BQA-1 and BQA-2) were prepared from quinoline, alpha'-dichloro-p-xylene and cis-1,4-dichloro-2-butene. The corrosion inhibitory property of BQA-1 and BQA-2 on Q235 steel in 1 mol/L hydrochloric acid solution and their adsorption behavior on Q235 steel surface were studied by means of mass loss measurement, electrochemical technique, scanning electron microscopy(SEM) and quantum chemical calculation. The mass loss results show that BQA-1 and BQA-2 had good corrosion inhibition effect on carbon steel in hydrochloric acid, when the mass concentration was 0.5 g/L and the temperature was 30 ℃, the inhibition efficiencies of BQA-1 and BQA-2 were both over 94.59%. In addition, the temperature rise resulted in a faster rate of desorption of BQA-2 than BQA-1. Electrochemical experiment results show that BQA-1 and BQA-2 are mixed type inhibitor and preferentially inhibited the cathodic reaction. Thermodynamic and activation energy parameters show that the adsorption of BQA-1 and BQA-2 on steel surface is spontaneous and exothermic, conforming to the Langmuir’s adsorption isotherm and mainly based on chemical adsorption. Quantum chemical calculation results show that the active sites of BQA-1 and BQA-2 are concentrated on the quinoline rings and heteroatom, and the ability of BQA-1 and BQA-2 molecules to accept electrons is greater than the ability to provide electrons.